<?php

require_once 'constants.php';
require_once 'Validate.php';
require_once 'Auth/Yadis/Yadis.php';
require_once 'OAuth.php';
require_once 'unsupportedserviceexception.php';
require_once 'remoteserviceexception.php';
require_once 'omb_yadis_xrds.php';
require_once 'helper.php';

/**
 * OMB service representation
 *
 * This class represents a complete remote OMB service. It provides discovery
 * and execution of the service’s methods.
 *
 * PHP version 5
 *
 * LICENSE: This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU Affero General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Affero General Public License for more details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 * @package   OMB
 * @author    Adrian Lang <mail@adrianlang.de>
 * @copyright 2009 Adrian Lang
 * @license   http://www.gnu.org/licenses/agpl.html GNU AGPL 3.0
 **/

class OMB_Service_Consumer {
  protected $url; /* The service URL */
  protected $services; /* An array of strings mapping service URI to
                          service URL */

  protected $token; /* An OAuthToken */

  protected $listener_uri; /* The URI identifying the listener, i. e. the
                              remote user. */

  protected $listenee_uri; /* The URI identifying the listenee, i. e. the
                              local user during an auth request. */

  /**
   * According to OAuth Core 1.0, an user authorization request is no full-blown
   * OAuth request. nonce, timestamp, consumer_key and signature are not needed
   * in this step. See http://laconi.ca/trac/ticket/827 for more informations.
   *
   * Since Laconica up to version 0.7.2 performs a full OAuth request check, a
   * correct request would fail.
   **/
  public $performLegacyAuthRequest = true;

  /* Helper stuff we are going to need. */
  protected $fetcher;
  protected $oauth_consumer;
  protected $datastore;

  /**
   * Constructor for OMB_Service_Consumer
   *
   * Initializes an OMB_Service_Consumer object representing the OMB service
   * specified by $service_url. Performs a complete service discovery using
   * Yadis.
   * Throws OMB_UnsupportedServiceException if XRDS file does not specify a
   * complete OMB service.
   *
   * @param string        $service_url  The URL of the service
   * @param string        $consumer_url An URL representing the consumer
   * @param OMB_Datastore $datastore    An instance of a class implementing
   *                                    OMB_Datastore
   *
   * @access public
   **/
  public function __construct ($service_url, $consumer_url, $datastore) {
    $this->url = $service_url;
    $this->fetcher = Auth_Yadis_Yadis::getHTTPFetcher();
    $this->datastore = $datastore;
    $this->oauth_consumer = new OAuthConsumer($consumer_url, '');

    $xrds = OMB_Yadis_XRDS::fromYadisURL($service_url, $this->fetcher);

    /* Detect our services. This performs a validation as well, since
       getService und getXRD throw exceptions on failure. */
    $this->services = array();

    foreach (array(OAUTH_DISCOVERY => OMB_Helper::$OAUTH_SERVICES,
                   OMB_VERSION     => OMB_Helper::$OMB_SERVICES)
             as $service_root => $targetservices) {
      $uris = $xrds->getService($service_root)->getURIs();
      $xrd = $xrds->getXRD($uris[0]);
      foreach ($targetservices as $targetservice) {
        $yadis_service = $xrd->getService($targetservice);
        if ($targetservice == OAUTH_ENDPOINT_REQUEST) {
            $localid = $yadis_service->getElements('xrd:LocalID');
            $this->listener_uri = $yadis_service->parser->content($localid[0]);
        }
        $uris = $yadis_service->getURIs();
        $this->services[$targetservice] = $uris[0];
      }
    }
  }

  /**
   * Get the handler URI for a service
   *
   * Returns the URI the remote web service has specified for the given
   * service.
   *
   * @param string $service The URI identifying the service
   *
   * @access public
   *
   * @return string The service handler URI
   **/
  public function getServiceURI($service) {
    return $this->services[$service];
  }

  /**
   * Get the remote user’s URI
   *
   * Returns the URI of the remote user, i. e. the listener.
   *
   * @access public
   *
   * @return string The remote user’s URI
   **/
  public function getRemoteUserURI() {
    return $this->listener_uri;
  }

  /**
   * Get the listenee’s URI
   *
   * Returns the URI of the user being subscribed to, i. e. the local user.
   *
   * @access public
   *
   * @return string The local user’s URI
   **/
  public function getListeneeURI() {
    return $this->listenee_uri;
  }

  /**
   * Request a request token
   *
   * Performs a token request on the service. Returns an OAuthToken on success.
   * Throws an exception if the request fails.
   *
   * @access public
   *
   * @return OAuthToken An unauthorized request token
   **/
  public function requestToken() {
    /* Set the token to null just in case the user called setToken. */
    $this->token = null;

    $result = $this->performAction(OAUTH_ENDPOINT_REQUEST,
                                  array('omb_listener' => $this->listener_uri));
    if ($result->status != 200) {
      throw OMB_RemoteServiceException::fromYadis(OAUTH_ENDPOINT_REQUEST,
                                                  $result);
    }
    parse_str($result->body, $return);
    if (!isset($return['oauth_token']) || !isset($return['oauth_token_secret'])) {
      throw OMB_RemoteServiceException::fromYadis(OAUTH_ENDPOINT_REQUEST,
                                                  $result);
    }
    $this->setToken($return['oauth_token'], $return['oauth_token_secret']);
    return $this->token;
  }

  /**
   *
   * Request authorization
   *
   * Returns an URL which equals to an authorization request. The end user
   * should be redirected to this location to perform authorization.
   * The $finish_url should be a local resource which invokes
   * OMB_Consumer::finishAuthorization on request.
   *
   * @param OMB_Profile $profile    An OMB_Profile object representing the
   *                                soon-to-be subscribed (i. e. local) user
   * @param string      $finish_url Target location after successful
   *                                authorization
   *
   * @access public
   *
   * @return string An URL representing an authorization request
   **/
  public function requestAuthorization($profile, $finish_url) {
    if ($this->performLegacyAuthRequest) {
      $params = $profile->asParameters('omb_listenee', false);
      $params['omb_listener'] = $this->listener_uri;
      $params['oauth_callback'] = $finish_url;

      $url = $this->prepareAction(OAUTH_ENDPOINT_AUTHORIZE, $params, 'GET')->to_url();
    } else {

      $params = array(
                'oauth_callback' => $finish_url,
                'oauth_token'    => $this->token->key,
                'omb_version'    => OMB_VERSION,
                'omb_listener'   => $this->listener_uri);

      $params = array_merge($profile->asParameters('omb_listenee', false). $params);

      /* Build result URL. */
      $url = $this->services[OAUTH_ENDPOINT_AUTHORIZE];
      $url .= (strrpos($url, '?') === false ? '?' : '&');
      foreach ($params as $k => $v) {
        $url .= OAuthUtil::urlencode_rfc3986($k) . '=' . OAuthUtil::urlencode_rfc3986($v) . '&';
      }
    }

    $this->listenee_uri = $profile->getIdentifierURI();

    return $url;
  }

  /**
   * Finish authorization
   *
   * Finish the subscription process by converting the received and authorized
   * request token into an access token. After that, the subscriber’s profile
   * and the subscription are stored in the database.
   * Expects an OAuthRequest in query parameters.
   * Throws exceptions on failure.
   *
   * @access public
   **/
  public function finishAuthorization() {
    OMB_Helper::removeMagicQuotesFromRequest();
    $req = OAuthRequest::from_request();
    if ($req->get_parameter('oauth_token') !=
          $this->token->key) {
      /* That’s not the token I wanted to get authorized. */
      throw new OAuthException('The authorized token does not equal the ' .
                               'submitted token.');
    }

    if ($req->get_parameter('omb_version') != OMB_VERSION) {
      throw new OMB_RemoteServiceException('The remote service uses an ' .
                                           'unsupported OMB version');
    }

    /* Construct the profile to validate it. */

    /* Fix OMB bug. Listener URI is not passed. */
    if ($_SERVER['REQUEST_METHOD'] == 'POST') {
      $params = $_POST;
    } else {
      $params = $_GET;
    }
    $params['omb_listener'] = $this->listener_uri;

    require_once 'profile.php';
    $listener = OMB_Profile::fromParameters($params, 'omb_listener');

    /* Ask the remote service to convert the authorized request token into an
       access token. */

    $result = $this->performAction(OAUTH_ENDPOINT_ACCESS, array());
    if ($result->status != 200) {
      throw new OAuthException('Could not get access token');
    }

    parse_str($result->body, $return);
    if (!isset($return['oauth_token']) || !isset($return['oauth_token_secret'])) {
      throw new OAuthException('Could not get access token');
    }
    $this->setToken($return['oauth_token'], $return['oauth_token_secret']);

    /* Subscription is finished and valid. Now store the new subscriber and the
       subscription in the database. */

    $this->datastore->saveProfile($listener);
    $this->datastore->saveSubscription($this->listener_uri,
                                       $this->listenee_uri,
                                       $this->token);
  }

  /**
   * Return the URI identifying the listener
   *
   * Returns the URI for the OMB user who tries to subscribe or already has
   * subscribed our user. This method is a workaround for a serious OMB flaw:
   * The Listener URI is not passed in the finishauthorization call.
   *
   * @access public
   *
   * @return string the listener’s URI
   **/
  public function getListenerURI() {
    return $this->listener_uri;
  }

  /**
   * Inform the service about a profile update
   *
   * Sends an updated profile to the service.
   *
   * @param OMB_Profile $profile The profile that has changed
   *
   * @access public
   **/
  public function updateProfile($profile) {
    $params = $profile->asParameters('omb_listenee', true);
    $this->performOMBAction(OMB_ENDPOINT_UPDATEPROFILE, $params, $profile->getIdentifierURI());
  }

  /**
   * Inform the service about a new notice
   *
   * Sends a notice to the service.
   *
   * @param OMB_Notice $notice The notice
   *
   * @access public
   **/
  public function postNotice($notice) {
    $params = $notice->asParameters();
    $params['omb_listenee'] = $notice->getAuthor()->getIdentifierURI();
    $this->performOMBAction(OMB_ENDPOINT_POSTNOTICE, $params, $params['omb_listenee']);
  }

  /**
   * Set the token member variable
   *
   * Initializes the token based on given token and secret token.
   *
   * @param string $token  The token
   * @param string $secret The secret token
   *
   * @access public
   **/
  public function setToken($token, $secret) {
    $this->token = new OAuthToken($token, $secret);
  }

  /**
   * Prepare an OAuthRequest object
   *
   * Creates an OAuthRequest object mapping the request specified by the
   * parameters.
   *
   * @param string $action_uri The URI specifying the target service
   * @param array  $params     Additional parameters for the service call
   * @param string $method     The HTTP method used to call the service
   *                           ('POST' or 'GET', usually)
   *
   * @access protected
   *
   * @return OAuthRequest the prepared request
   **/
  protected function prepareAction($action_uri, $params, $method) {
    $url = $this->services[$action_uri];

    $url_params = array();
    parse_str(parse_url($url, PHP_URL_QUERY), $url_params);

    /* Add OMB version. */
    $url_params['omb_version'] = OMB_VERSION;

    /* Add user-defined parameters. */
    $url_params = array_merge($url_params, $params);

    $req = OAuthRequest::from_consumer_and_token($this->oauth_consumer,
                                      $this->token, $method, $url, $url_params);

    /* Sign the request. */
    $req->sign_request(new OAuthSignatureMethod_HMAC_SHA1(),
                                           $this->oauth_consumer, $this->token);

    return $req;
  }

  /**
   * Perform a service call
   *
   * Creates an OAuthRequest object and execute the mapped call as POST request.
   *
   * @param string $action_uri The URI specifying the target service
   * @param array  $params     Additional parameters for the service call
   *
   * @access protected
   *
   * @return Auth_Yadis_HTTPResponse The POST request response
   **/
  protected function performAction($action_uri, $params) {
    $req = $this->prepareAction($action_uri, $params, 'POST');

    /* Return result page. */
    return $this->fetcher->post($req->get_normalized_http_url(), $req->to_postdata(), array());
  }

  /**
   * Perform an OMB action
   *
   * Executes an OMB action – to date, it’s one of updateProfile or postNotice.
   *
   * @param string $action_uri   The URI specifying the target service
   * @param array  $params       Additional parameters for the service call
   * @param string $listenee_uri The URI identifying the local user for whom
   *                             the action is performed
   *
   * @access protected
   **/
  protected function performOMBAction($action_uri, $params, $listenee_uri) {
    $result = $this->performAction($action_uri, $params);
    if ($result->status == 403) {
      /* The remote user unsubscribed us. */
      $this->datastore->deleteSubscription($this->listener_uri, $listenee_uri);
    } else if ($result->status != 200 ||
               strpos($result->body, 'omb_version=' . OMB_VERSION) === false) {
      /* The server signaled an error or sent an incorrect response. */
      throw OMB_RemoteServiceException::fromYadis($action_uri, $result);
    }
  }
}
